For the purpose of measuring the fill level of liquids and solids in containers, a fill-level measuring device is usually installed at or in the container wall. The fill-level measuring device subsequently transmits waves, either in a guided manner through a waveguide, or in a radiated manner by way of an antenna device of the product. Subsequently, the waves reflected by the product are received by the measuring device. From the transit time that can be determined therefrom, the distance between the sensor and the product results, and from the knowledge of the relative position of the sensor from the container bottom, the sought fill height can be derived.
The measured data, if applicable after buffer storage and/or initial evaluation, is transmitted to a control- or evaluation device. The device may also simply be a display device. As a countermove to the above, the field devices may be parameterised or triggered (i.e. to cause a measuring operation) by way of the control device. This bi-directional data exchange may require data transmission paths, by way of which the field devices are coupled to the control devices, read-out devices or display devices.
As a rule, the individual components of field device and evaluation-/display device or control device may be installed so as to be fixed. The field device is, for example, located on the cover of a high product container and is connected, by way of a data cable, to an evaluation-/display unit or control device arranged in a control room. Device parameterisation or reading the measuring data is thus only possible directly on the field device or in the control room.